absbestos dust is the killer, use a pesticide type spray bottle to keep everything wet with water as you work, along with canister type masks. -they're 30 each, and beats meso in the lungs. You'll need the sprayer for any wallpaper removal later.
as for the pex - it's pressure rating is VERY tempt dependent. I have it in my studio for air. It is awesome stuff though, and extremely easy to work with. Make sure you use the pressure shock dampers though, to mitigate movement on the new runs. Ask me how I know.
Good work sir. keep plugging.
a near-death experience is just god following "catch and release" regulations...
john (johnny) henley